It has hitherto been proposed to use various inorganic particles as a material combined with cosmetics for improving their spreadability. Spherical calcium carbonate is one of them. The spherical calcium carbonate itself, however, has poor stability in water, and thus it has been proposed that the spherical calcium carbonate is surface-treated with a higher fatty acid such as stearic acid (see Patent Literature 1).
In particular, in the case of cosmetics such as foundation makeup, it is strongly required for inorganic particles combined therewith to be superior in water repellency in order to prevent makeup from smearing with perspiration. However, even if the spherical calcium carbonate is surface-treated with a higher fatty acid or a salt thereof as described above, it is not sufficient in water repellency, and it is not sufficient in feel, either.
Then, for example, a method is proposed in which (extender) pigment particles including calcium carbonate are coated with organopolysiloxane such as organohydrogen polysiloxane or diorganopolysiloxane to obtain a surface-treated (extender) pigment for use in cosmetics (see Patent Literature 2).
According to the method described above, however, the organopolysiloxane is emulsified with a surfactant, a(n) (extender) pigment is mixed with the resulting emulsion, and the mixture is heated, dried, and crushed to obtain a surface-treated (extender) pigment for use in cosmetics. Thus, the method has many production steps and is complicated, and moreover, when calcium carbonate is used as the pigment, it is difficult to directly form an organopolysiloxane coating in an effective amount on the surfaces of the calcium carbonate particles. Furthermore, the water repellency and slipperiness of surface-treated (extender) pigment for use in cosmetics have not been quantitatively evaluated. They have been only insufficiently studied.